A basic round of small arms ammunition, particularly rifle ammunition, commonly comprises a case having a primer disposed in a closed end thereof and adapted to receive a quantity of gun powder interiorly thereof. The case includes an open end adapted to receive therein a projectile (also commonly referred to as a “bullet”). Among other things, the depth to which the projectile is inserted into the case desirably produces an overall length of the case and projectile projecting therefrom which is consistently constant from round to round of ammunition of a given type, size, etc.
These projectiles commonly comprise a cup-shaped metal jacket (e.g. copper or brass) having a closed end and an open end. A core, usually of a metal, a compressed powdered metal, or a compressed mixture of two or more powdered metals, is inserted into the jacket. In one example, all of the core is fully contained within the jacket, leaving a portion of the jacket at its open end essentially void of core material. In this example, the open end of the jacket (and at times a portion of the core disposed within the jacket) are die-formed to define an ogive on the leading end of the jacket/core subassembly. In the course of forming the ogive, the open end of the jacket is not fully closed, thereby defining a meplat cavity and an associated meplat opening within the region of the ogive on the leading end of the projectile. In another example, the core is disposed within the jacket and the jacket is formed about the core thereby providing a projectile commonly referred to as a full metal jacket (FMJ) projectile. The present invention addresses the enhancement of the external ballistics and ensures consistent terminal ballistics of either of these types of projectiles.
More specifically, in certain situations, projectiles employed in weapons desirably impart massive destructive forces to an intended target. To this end, it has been heretofore common to provide an “open tip” in the leading end of a lead slug fired from a pistol or rifle. In many instances, the lead slug is covered, fully or partially with a metal jacket, such as copper, brass, or alloy material, and the “open tip” is defined in the leading end of the jacket so that when the leading end of the projectile strikes a target, such as the body of an animal, hydraulic pressure builds up in the open tip of the projectile, causing the projectile to “expand”, “tear apart into multiple pieces” or otherwise create multiple relatively small units which individually destroy tissue, bones, etc. of an animal, for example.
Of the many ogived projectiles of the prior art, a majority of the projectiles include a meplat cavity defined in the leading end of the projectile and within the region of the ogive. This meplat cavity includes a meplat opening which leads from interiorly of the meplat cavity outwardly to the ambient environment. Functionally, the meplat cavity serves to enhance the expansion of the projectile upon it striking a target, hence enhancement of the terminal ballistics of the projectile. Such expansion occurs when the projectile strikes a target, such as an animal, and hydraulic pressure builds up within the meplat cavity, causing the ogive region of the projectile to commence deformation and/or disintegration of the projectile, such deformation and/or disintegration being propagated inwardly of the projectile along its length with resultant major deformation and/or disintegration of the projectile within the target. The performance of the projectile upon and following its striking of a target is referred to as “terminal ballistics” of the projectile. The performance of the projectile during its flight from the muzzle of the weapon to its impact with a target is referred to as the “external ballistics” of the projectile.
It has been proposed heretofore that the overall length of a projectile useful in the manufacture of small arms ammunition, be made uniform in an effort to enhance the flight of a projectile from a weapon barrel to a target. This prior practice is accomplished merely by trimming away excess metal jacket material from the leading end of the jacket after the projectile has been formed, employing a hand-operated trimming tool. This prior art technique effects a shortening of the overall length of the finished projectile. Coincidentally this prior art operation further tends to develop a flat annular face on the leading end of the projectile. The present inventors have found that this flat face of the projectile formed by the prior art techniques, is neither uniform in the thickness of the annular aspect of the face, nor is the plane occupied by the flat face necessarily perpendicular to, nor concentric with, the longitudinal centerline of the elongated projectile. More specifically, the metallic jackets commonly employed in the formation of a core-based projectile frequently exhibit differing wall thickness of the jackets. This variance in wall thickness may exist within a given lot of jackets as well as from lot to lot of jackets.
Moreover, in the process of forming an ogive on the leading end of a projectile, there occurs major displacement and/or movement (flow) of the metallic jacket material within the leading end of the jacket and in the region of the ogive. Such action most often results in non-uniform distribution of such displaced or moved jacket material and therefore non-uniformity of the wall thickness of the jacket within the region of the ogive. In the prior art practice of cutting away a portion of the leading end of a projectile to establish an overall length of the projectile and its case (i.e., a round of ammunition) the thickness of the jacket proximate the leading end of the jacket is increased or decreased as a function of the uniformity of the wall thickness of the jacket within the region of the ogive, i.e., within the region of the meplat cavity. This thickness of the leading end of the jacket may increase in a direction along the ogive and away from the leading end of the jacket, Thus, when employing the prior technique of flattening the leading edge of the jacket in order to gain the selected desired overall length of the projectile, more or less of the length of the jacket is cut away, resulting in undesirable variances in wall thickness of a given projectile and also from projectile to projectile at the annular flattened face of the leading end of projectile. Thus when the projectile is fired from a weapon, this annular flat face impacts the ambient air mass external and contiguous to the muzzle of the weapon at some uncertain orientation of the flat face relative to the flight path of the projectile. Moreover, the non-uniformity of the thickness of the annular aspect of the flat face of the projectile presents a non-consistent area of impact with the ambient air mass along the circumference of the annular face. Whereas the trimming of the leading end of the projectile to develop a consistent overall length of the projectile (and ultimately consistent uniformity of the overall length of the round of ammunition formed therefrom) reportedly serves to enhance the uniformity of flight of the projectile from the weapon barrel to the target as compared to a non-trimmed projectile, this prior art fails to fully address the uniformity of flight of the projectile and, importantly, also fails to address the issue of the terminal ballistics of the projectile when it strikes a target. Neither does this prior art address the ballistics coefficient of the projectile, all of which are of major concern when employing projectiles having a meplat opening and/or meplat cavity defined in the leading end of the projectile. Such meplat cavities and their associated outwardly facing opening are not only critical in establishing the accuracy of delivery of a projectile to an intended target, the present inventor has found that they also are critical for purposes of establishing the degree of penetration of the projectile into a given target, effecting expansion (frangibility) of the projectile when it strikes a target, and effecting the desired destruction of the target in addition to their effects upon the flight of the projectile to its intended target.